Story Highlights

Try to get Nancy Avitabile to commit to when she has done her strongest racing. 15 years ago? No. 5 years ago? No.

The best might be when she next crosses the finish line. The 64-year-old triathlete keeps getting faster, sprinting past aging as quickly and gracefully as she does past other runners. She has been competing in triathlons for 16 years.

On Oct. 22, she races in the World Triathlon Championship in Auckland, New Zealand. She's the oldest competitor in the 60-64 age group. She won the national championship in her age group in August in 2 hours, 45 minutes and 35 seconds (one mile swim: 34 minutes, 38 seconds; 25-mile bike: one hour, 16 minutes; 10K run: 51 minutes, 40 seconds). Her swim in the New York City Triathlon in July was her fastest ever there in seven years (18 minutes, 40 seconds). Last year, she had her fastest 10K run in decades, 48:28 (or 7:48 minutes per mile) at the Pike's Peek 10K in Rockville, Md.

"It's strange that I'm getting older and still getting faster,'' says Avitabile. "But I like that I get to push my body in three very different sports. I like the cross-training."

She credits her ability to the total body conditioning of triathlons to three things: good genetics, mental toughness and smarter training.

How to train smarter? "Building a strong core as well as strong legs and upper body has been essential to me as I've gotten older," she says. "Injuries can really set older people back. I keep my muscles strong to avoid injuries."

She works with a strength trainer several days a week.

"I have found that if my legs start to get tired when I'm on the bike or when I'm running, my core can help push me through,'' she says.

Muscle slowly starts to vanish as we age, declining as much as 1% a year beginning in our 20s and 30s, says athletic trainer Kent Biggerstaff, a member of National Athletic Trainers' Association. Biggerstaff works with senior pro golfers. Before that he worked with Major League Baseball teams. He also works with older people in assisted-living facilities.

One thing he notices is that many people hurt a knee or hip at some point in their lives and start to favor it.

"Balancing the body out is important,'' says Biggerstaff. "Once you start favoring one side of your body, you can fatigue it at some point, and fatigue can lead to an injury."

One way to check both sides, he says is by performing this test at home: Put your back against the wall with your feet 18 to 20 inches in front of you; squat down part way; lift up your left leg and hold it off the ground for 15 seconds and then return your foot to the ground; lift up your right leg for 15 seconds and return it to the ground.

"Many people can't hold one side up for very long at all,'' says Biggerstaff. "You can strengthen the muscles by doing a series of those exercises, though. It works your quadriceps, hip muscles and the glutes."

Biggerstaff says those stomach muscles that waste away quickly in middle age need your attention. He gets the senior golfers to work on their abs by having them do crunches while balancing on exercise balls,

"Working on a ball and having to balance on it requires other smaller muscles to be strengthened,'' he says.

Avitabile says she used to have an imbalance in her quads, but corrected it and never skips her time at the health club. She does know one other thing is important as people age.

"I've finally got to accept rest days — one a week during racing season — and off-season months, usually two months of no training after my last race,'' she says.

Otherwise, she's out there training. She gets up in the dark to put in her time running before she goes to work. She owns an accounting business. She cycles with a men's cycling club because "they push me and don't let me make mistakes."

At the Nation's Triathlon in Washington, D.C. on Sept. 11, 2011, she had a 1:07:41 bike time "which meant I was going 22 miles per hour for 25 miles."

And if everything is right in New Zealand, maybe she'll see a new personal best.